Stepping up the search for life among the stars NASA to intensify scan for radio signals

November 23, 1991|By Douglas Birch

GREEN BANK,W.VA. — GREEN BANK, W.Va. -- It could be a crucial moment in human history, the start of a new age of exploration that leads to discoveries eclipsing those of Columbus. Or it may be an interstellar wild goose chase.

Next Columbus Day, after almost two decades of skepticism and debate, the National Aeronautics and Space Administration plans to launch a seven-year, $100 million effort to scan the heavens for the equivalent of two little words: "Greetings, Earthlings."

The program, called the Search for Extra-Terrestrial Intelligence, or SETI, will be the most ambitious effort so far to pick up radio signals from beings outside our solar system.

"It would probably be the biggest advance since the birth of language," said astronomer Eric J. Chaisson, senior scientist at Baltimore's Space Telescope Science Institute, who sat on the panel that helped plan the search.

For the first few years, all SETI work will involve borrowing radio telescopes normally used for astronomy or satellite tracking.

But in 1995, when a huge new radio telescope is completed at the National Radio Astronomy Observatory here, SETI astronomers will get the full-time use of the NRAO's current workhorse -- a 140-foot-wide, white steel dish that looms above the farmland in this isolated Appalachian valley.

Observatory Director George Seielstad, who navigates a battleship-gray diesel sedan (the spark plugs in gasoline-powered engines cause radio noise) around the observatory grounds, is typical of many astronomers in that he has come to suspect that life probably has developed on planets orbiting other stars.

And on some of those planets, he thinks, intelligent life probably has built technological societies.

But the odds against finding those civilizations, he figures, are -- well, astronomical.

Even if extraterrestrial civilizations pepper the starry night, scientists speculate, they may not want to advertise themselves. Or they might be too advanced, or not advanced enough, to use radio signals.

Or their signals may be drowned out by the rising babble of

earthly radio transmissions, especially those produced by the world's military forces and the growing number of global communications satellites.

RTC Or those cultures may simply be scattered too thinly in what scientists call the "cosmic haystack" -- the universe's billions of galaxies, each containing hundreds of billions of stars.

Dr. Chaisson, a former member of the panel of astronomers that planned the SETI project, compared the task to sifting the sands of the Atlantic beaches by hand in search of a single small diamond.

Still, many scientists support the hunt.

"The reward is so enormous," Dr. Seielstad says, "it's such a significant discovery that you have to find out. As humans, our intellectual curiosity sort of demands we find out if this is true.

"At least this set of measurements will let us know something," he says. "You're trying. You're not just speculating. It's not just asking how many angels can dance on the head of a pin."

Up until the 1980s, the scientific community generally was skeptical of the notion of a government-sponsored search for alien radio transmissions, and scornful members of Congress repeatedly blocked funding.

As late as last spring, the House killed NASA's $12.5 million appropriation for SETI in fiscal 1992, and Sen. Richard H. Bryan, D-Nev., moved to shift the money to social programs, calling the NASA effort "superfluous."

On Oct. 12 of next year, NASA plans to launch SETI's two phases at separate radio observatories.

The so-called "targeted search," directed by NASA's Ames Research Center in Mountain View, Calif., will begin at the world's largest radio telescope -- a 1,000-foot-wide dish built into the top of a mountain in Arecibo, Puerto Rico.

Using a computer system that monitors 10 million channels at once, scientists will scour the frequency range from 1,000 to 3,000 megahertz from 1,000 stars.

All those stars are between about 4 light-years and 80 light-years from Earth, our near neighbors in the Milky Way galaxy. (A light year is the distance light travels in a year, roughly 6 trillion miles.)

SETI's other phase, the all-sky survey, will be run by the Jet Propulsion Laboratory in Pasadena, Calif., and begin at NASA's Deep Space Network radio observatory in Goldstone, Calif.

JPL scientists plan to spend five years aiming NASA's global array of 112-foot Deep Space Network telescopes at broad areas of space, looking for signals in the 1,000- to 10,000-megahertz range.

In the first half-hour of its operation, NASA's SETI is expected to scour more radio channels for extraterrestrial signals than professional and amateur astronomers around the globe have managed since 1960.